Cascaded Reference Circuit for Low Noise Wearable Sensing
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Solution Overview
Problem
Current wearable devices are not convenient for everyday life activities and fail to accurately and continuously measure stress with the accuracy of medical devices, as they require more power and are not practical for continuous use due to their size and power consumption.
Innovation Solution
The development of wearable devices that use a cascaded reference system to measure electrovesselgram (EVG) and subdermal spectrogram (SSG) signals with minimal power consumption, allowing for real-time feedback and detection of physiological stress indicators, even when worn on the wrist or other appendages, using a unique configuration that cancels out ambient and system noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wearable devices use traditional sensing circuits to measure stress, then they can detect physiological signals, but they consume too much power and are not practical for continuous use
Solution Approach 1:
The patent converts the harmful ambient noise and power supply noise into a beneficial reference signal by cascading reference generators. The first reference generator creates a reference signal from power supply noise, and the second reference generator combines this with ambient noise to create a composite reference that actively cancels out interference, thereby reducing the need for high-power filtering circuits and enabling lower power consumption while maintaining continuous monitoring capability
2Ease of operation
If wearable devices are made smaller and lower power, then they are more convenient for everyday use, but they cannot achieve medical device accuracy for stress measurement
Solution Approach 1:
The patent turns the typically harmful noise from power supplies and ambient environment into a useful reference signal. By using cascaded reference generators, the system creates reference signals that match the noise characteristics of the measurement environment, allowing for noise cancellation that enables medical-grade accuracy in small, low-power wearable devices without requiring large, power-intensive filtering systems
Solution Approach 2:
The patent changes the approach to noise handling by transforming fixed, high-power filtering designs into adaptive reference signal generation. The reference generators dynamically create signals based on power supply characteristics and ambient noise conditions, allowing the system to maintain measurement precision across varying operational conditions while using minimal power
3Productivity
If wearable devices continuously monitor stress throughout the day, then they provide comprehensive stress management data, but they require more power and are not practical for extended wear
Solution Approach 1:
The patent enables continuous monitoring by using the cascaded reference system to maintain signal quality throughout the day without requiring frequent charging. The reference generators continuously compensate for noise and interference, allowing the device to operate at low power levels while providing uninterrupted stress monitoring data from morning to night
Solution Approach 2:
The system converts the ever-present power supply noise and ambient interference into a beneficial reference signal that enables continuous operation. By actively referencing and canceling these noise sources, the device can maintain accurate measurements without requiring high power consumption, making extended continuous wear practical
Data Source
AI summary
This disclosure provides cascaded reference circuits and low amplitude signal sensing circuits that are useful in applications where high sensitivity, low noise measurements are needed. Such embodiments may be especially useful in health and fitness wearable devices. Systems incorporating the circuits, as well as methods for using these circuits to determine quantities and qualities of a person's moods, such as how much and what kinds of stress they experience. The provided devices are useful on limbs and appendages, such as in a smart watch that is worn on the wrist. Methods are provided for using the devices of this disclosure to privately alert wearers to an increase in bad stress in the moment when they can take actions to reduce their stress and physiological stress responses. These devices are useful for measuring and increasing the effectiveness of relaxation techniques. As a result of using methods and devices of this disclosure, people are healthier, they make more response-able decisions, and relationships improve.